Beam Loss Measurements for Recurring Fast Loss Events During 2017 LHC Operation Possibly Caused by Macroparticles

Lechner, Anton; Auchmann, Bernhard; Bravin, E.; Gorzawski, Arkadiusz; Grob, Laura; Holzer, Eva Barbara; Lindstrom, Bjorn Hans Filip; Medvedeva, T.; Mirarchi, Daniele; Schmidt, R.; Valette, Matthieu; Wollmann, Daniel

doi:10.18429/jacow-ipac2018-tupaf040

Cited by 5 publications

(3 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The collision vertex can therefore be determined empirically by finding the best match between measured and simulated patterns. This method already proved to be successful for localizing the aforementioned obstacle in the dispersion suppressor [24] as well as the location of accidental air inflow in one of the arc cells [27]. The same approach was also used in run I for estimating the location of dust events at 3.5 TeV and 4 TeV in a specific arc cell equipped with additional BLMs [40].…”

Section: B Methods For Reconstructing the Number Of Collisionsmentioning

confidence: 99%

“…[40], by recording the energy deposition in the sensitive gas volume between the electrodes of the BLM model. The dust particles were assumed to be static and pointlike [27,40].…”

Section: B Methods For Reconstructing the Number Of Collisionsmentioning

confidence: 99%

“…For run III, optimistic and pessimistic values are given for the transverse emittance (BCMS beams), whereas the bunch intensity is the maximum intensity expected in run III [31]. The last column shows nominal HL-LHC beam parameters for standard 25 ns beams [28] [24][25][26][27]. The latter were leftovers from an accidental air inflow in a certain arc cell.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Study of dust-induced beam losses in the cryogenic arcs of the CERN Large Hadron Collider

Lechner,

Bélanger,

Efthymiopoulos

et al. 2021

Preprint

View full text Add to dashboard Cite

The interaction of dust particles with the LHC proton beams accounts for a major fraction of irregular beam loss events observed in LHC physics operation. The events cease after a few beam revolutions because of the expulsion of dust particles from the beam once they become ionized in the transverse beam tails. Despite the transient nature of these events, the resulting beam losses can trigger beam aborts or provoke quenches of superconducting magnets. In this paper, we study the characteristics of beam-dust particle interactions in the cryogenic arcs by reconstructing key observables like nuclear collision rates, loss durations and integral losses per event. The study is based on events recorded during 6.5 TeV operation with stored beam intensities of up to ∼ 3 × 10 14 protons per beam. We show that inelastic collision rates can reach almost 10 12 collisions per second, resulting in a loss of up to ∼ 1.6 × 10 8 protons per event. We demonstrate that the experimental distributions and their dependence on beam parameters can be described quantitatively by a previously developed simulation model if dust particles are assumed to be attracted by the beam. The latter finding is consistent with recent time profile studies and yields further evidence that dust particles carry a negative charge when entering the beam. We also develop different hypotheses regarding the absence of higher-loss events in the measurements, although such events are theoretically not excluded by the simulation model. The results provide grounds for predicting dust-induced beam losses in presence of higher-intensity beams in future runs of the High-Luminosity LHC.

show abstract

Section: B Methods For Reconstructing the Number Of Collisionsmentioning

confidence: 99%

“…[40], by recording the energy deposition in the sensitive gas volume between the electrodes of the BLM model. The dust particles were assumed to be static and pointlike [27,40].…”

Section: B Methods For Reconstructing the Number Of Collisionsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation